The invention relates to a two-way valve, particularly for a liquid dispenser, having a first connection for a liquid reservoir, a second connection for a pump for suction or compression and a third connection for a liquid consuming means, a diaphragm disk being clamped at its radially outer annular edge between a valve housing and a cover housing and engages flat against an annular seat, in whose vicinity is located an axial opening for the liquid and on which on the cover side the diaphragm disk engages against a mating annular seat having the same diameter.
Such a two-way valve is known from an earlier dated, but not previously published DE 198 16 398 A1 having a first connection for a medicament reservoir, a second connection for a suction or compression pump (with piston) and a third connection for a liquid consuming means. A similar construction can be gathered from U.S. Pat. No. 4,246,932.
DE 196 43 360 C1 discloses a diaphragm disk clamped with a full cross-section on its radially outer annular edge between a valve housing and a cover housing and which is engaged against an annular seat. In the vicinity of the annular seat is provided an axial opening for the liquid and on the cover side the diaphragm disk rests against another annular seat.
Such two-way valves are used in the medicine and hygiene fields e.g. for infusers, spray containers, etc. or in liquid dispensers for liquid soaps, creams, suspensions of all types, cleaning agents, detergents, gels, ointments, etc. The term liquid is here understood to cover all types of fluids, particularly also suspensions of solids in fluids and gels, foams, etc.
The pump systems used for this purpose are in each case based on a unit constituted by a connecting piece, sealing housing, piston with compression spring and a ball. Since for weight and cost reasons the balls are made from steel or stainless steel, undesired physicochemical reactions occur between the liquid and the steel material, so that when a medicament comes into contact with the ball molecular processes occur, which modify the medicament and consequently prevent the use of such a system.
Diverging from the known steel ball-compression spring system and based on two-way valves with diaphragm disks, the problem of the invention is to provide a two-way valve with spring-loaded piston through which individual portions can be metered and discharged.
According to the invention the set problem is solved in that between the radially outer annular edge and a radially smaller diameter annular seat is provided an additional bilateral clamping of the centrally open diaphragm disk, comprising the mating annular seat and an annular seat and that in addition to the additional clamping of the first connection a first annular channel is formed, which issues into the third connection. Thus, during a suction stroke of the piston the liquid is sucked and by a following compression stroke is conveyed through the third connection for the liquid consuming means. Liquid transport can take place in matched quantities as a function of the viscosity of the liquid.
According to a development, between the radially outer annular edge of the diaphragm disk and the additional, radially inner clamping, the diaphragm disk engages against a unilateral, valve housing-side, annular bearing surface, so that a further valve seat is created, so that in principle two valves are combined in the two-way valve.
According to other features, the annular bearing surface on the valve housing is faced by an annular channel of the cover housing. The advantage is the creation of an adequately large volume flow channel.
According to a further development, within the valve housing and radially adjacent to the bearing surface, is provided a connection channel facing the annular channel of the cover housing. The connection channel ensures an adequately large flow-connection for removing the liquid in the third connection.
The provision of an adequately large flow cross-section is helped by the fact that on the side of the valve housing the annular connection channel has an axial length greater than the radial width. The greater axial length corresponds to the diameter of the flow channel in the third connection.
The provision of favourable flow cross-sections is also helped by the fact that at a circumferential point the annular channel is connected by a channel section in the cover housing surrounding the diameter of the diaphragm disk and a similar channel section in the valve housing to the connection channel. This measure also helps to create an independent flow channel for the piston compression process.
According to an improvement, within the cover housing the annular seat is formed by means of an inwardly hollow recess of a core part of the cover housing, which creates the aforementioned annular seat for the diaphragm disk.
According to further features of the invention around the core part of the cover housing are arranged individual annular segmental recesses or several cylindrical holes, which link the first connection to the centre when the valve is open.